Department of Orthopedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325000, P R China; Department of Pharmacy, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325000, P R China.
Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech), Nanjing 211816, P R China.
Acta Biomater. 2020 Jun;109:153-162. doi: 10.1016/j.actbio.2020.04.001. Epub 2020 Apr 24.
A major obstacle in osteoarthritis (OA) theranostics is the lack of a timely and accurate monitoring method. It is hypothesized that the loss of anionic glycosaminoglycans (GAGs) in articular cartilage reflects the progression of OA. Thus, this study investigated the feasibility of photoacoustic imaging (PAI) applied for monitoring the in vivo course of OA progression via GAG-targeted cationic nanoprobes. The nanoprobes were synthesized through electrostatic attraction between poly-l-Lysine and melanin (PLL-MNPs). Cartilage explants with different concentrations of GAGs incubated with PLL-MNPs to test the relationship between GAGs content and PA signal intensity. GAG activity was then evaluated in vivo in destabilization of the medial meniscus (DMM) surgically-induced mouse model. To track OA progression over time, mice were imaged consistently for 10 weeks after OA-inducing surgery. X-ray was used to verify the superiority of PAI in detecting OA. The correlation between PAI data and histologic results was also analyzed. In vitro study demonstrated the ability of PLL-MNPs in sensitively detecting different GAGs concentrations. In vivo PAI exhibited significantly lower signal intensity from OA knees compared to normal knees. More importantly, PA signal intensity showed serial reduction over the course of OA, while X-ray showed visible joint destruction until 6 weeks. A decrease in GAGs content was confirmed by histologic examinations; moreover, histologic findings were well correlated with PAI results. Therefore, using cationic nanoprobe-enhanced PAI to detect the changes in GAG contents provides sensitive and consistent visualization of OA development. This approach will further facilitate OA theranostics and clinical translation. STATEMENT OF SIGNIFICANCE: The study of in vivo monitoring osteoarthritis (OA) is of high significance to tracking the trajectory of OA development and therapeutic monitoring. Here, we developed a cartilage-targeted cationic nanoprobe, poly-l-Lysine-melanin nanoparticles (PLL-MNPs), enhancing photoacoustic imaging (PAI) to monitor the progression of OA. The in vitro study demonstrated the ability of PLL-MNPs to detect different concentrations of GAGs with high sensitivity. We found that the contents of GAGs in vivo steadily decreased from the development of OA initial-stage to the end-point of our investigation via PAI; it reflected the course of OA in living subjects with high sensitivity. These results allow for further development in various aspects of OA research. It has potential for clinical translation and has a great impact on personalized medicine.
骨关节炎（OA）治疗学的一个主要障碍是缺乏及时和准确的监测方法。据推测，关节软骨中阴离子糖胺聚糖（GAG）的丢失反映了 OA 的进展。因此，本研究通过靶向 GAG 的阳离子纳米探针，研究了光声成像（PAI）用于监测 OA 进展过程的可行性。纳米探针通过聚-L-赖氨酸和黑色素（PLL-MNPs）之间的静电吸引合成。将具有不同 GAG 浓度的软骨外植体与 PLL-MNPs 孵育，以测试 GAG 含量与 PA 信号强度之间的关系。然后在通过内侧半月板不稳定（DMM）手术诱导的小鼠模型中体内评估 GAG 活性。为了随时间跟踪 OA 进展，在 OA 诱导手术后持续对小鼠进行 10 周成像。X 射线用于验证 PAI 在检测 OA 方面的优越性。还分析了 PAI 数据与组织学结果之间的相关性。体外研究表明 PLL-MNPs 能够灵敏地检测不同 GAG 浓度。体内 PAI 显示 OA 膝关节的信号强度明显低于正常膝关节。更重要的是，PA 信号强度在 OA 过程中呈系列降低，而 X 射线显示关节破坏直到 6 周。组织学检查证实 GAG 含量降低；此外，组织学发现与 PAI 结果密切相关。因此，使用阳离子纳米探针增强的 PAI 检测 GAG 含量的变化可提供对 OA 发展的敏感且一致的可视化。这种方法将进一步促进 OA 治疗学和临床转化。研究意义：体内监测骨关节炎（OA）的研究对于跟踪 OA 发展轨迹和治疗监测具有重要意义。在这里，我们开发了一种靶向软骨的阳离子纳米探针，即聚-L-赖氨酸-黑色素纳米颗粒（PLL-MNPs），增强光声成像（PAI）以监测 OA 的进展。体外研究表明，PLL-MNPs 具有高灵敏度，能够检测不同浓度的 GAG。我们发现，通过 PAI，体内 GAG 含量从 OA 初始阶段到我们研究的终点稳定下降；它以高灵敏度反映了活体受试者的 OA 过程。这些结果允许在 OA 研究的各个方面进一步发展。它具有临床转化的潜力，对个性化医疗有重大影响。
